Conversely, the restriction factor SAMHD1 (targeted by some HIV-2/SIV Vpx and Vpr variants, but not HIV-1 [Hrecka et al., 2011; Laguette et al., 2011; Lim et al., 2012]) is depleted by T cell activation, independent of HIV infection (Figure 2C, right panel). The gene discussed is SAMHD1; the disease is HIV infectious disease.